Sound reproducing and amplifying device



Sept 4, 1945- c. F. DILKS 2,384,371

SOUND REPRODUCING AND AMPLIFYING DEVICE Filed May 28, 1941 2 Sheets-Sheet 2 Patented Sept. 4, 1945 UNITED s'm'rss PATENTom-ms SOUND REPRODUCIN G AND AMPLIFYING DEVICE Charles F. Dilks, South Norwalk, Conn.

Application May 28, 1941, Serial No. 395,510

8 Claims.

My present invention relates to sound reproducing devices, and more particularly to an improved combined sound reproducing and amplilying device and to an improved valve mechanism for use therein.

As the basic principle of sound-is pressure, it naturally follows that the greater the pressure, and the more such pressure is concentrated, the more intense will be the sound emanating at such point of concentration. A diaphragm at rest creates no pressure above atmosphere, but when placed in motion. under the influence of sound waves. it does create a small pressure by fanning or beating the atmosphere.

Since the basic principle of sound is pressure. it is only necessary to characterize or modulate this pressure in order to generate a sound, and the energy of the generated sound will depend on the pressure and the modulation. In the present invention the pressure is generated at one pointas by a pump-and the character is generated at another point-as by an amplifier. Both the pressure and character are arranged to occupy the same point-a valvHimultaneousiy. The character in the form of electrical impulse vibrates the valve to permit flow of air under pressure through the valve in accordance with the character.

In a diaphragm, pressure is evenly distributed over its entire surface, and it is desirable that any diaphragm employed be as small as is possible. In my present device the energy generated is concentrated within an area no greater than the opening of the horn inlet.

My present invention relates to that class of device wherein sound waves are reproduced and amplified by the aid of a fluid, such as air under pressure. In carrying out my present invention the sound to-be reproduced is transmitted to a voice coil. This voice coil operates an air valve for controlling the emission of air under pressure to thus amplify to any degree desired the sound waves which are being reproduced.

Preferably, the voice coil and the valve operated thereby are located within a closed chamber associated with means for supplying air under pressure and with means for maintaining the pressure of the air within the chamber substantially constant. The transmitter for transmitting the voice currents to the voice coil is located without the chamber, and may be located at any desired distance therefrom.

The valve for controlling the emission of air from the chamber is located within the chamber and hence is positioned on the pressure side of the valve.

The valve for controlling the emission of air from the chamber may be connected to and is preferably formed integral with an armature controlled by the voice coil. Connected to the armature and thus to the valve, is an air pressure regulator comprising an arm connected to the armature and in turn connected to a diaphragm.

In operation, and for the reproduction and ampliflcation of, for example, music, it is preferable that the pressure within the chamber be below seven and one-half (7%) pounds per square inch, and for speech or signalling purposes the pressure may be anything desired, depending upon the.

degree of amplification desired. such pressure in the latter event may range from twenty (20) to thirty (30) pounds per square inch, or even higher.

A feature of my invention is an improved valve for controlling the flow of air under pressure to amplify sound waves.

Another feature of the invention is an improved valve structure in combination with means for operating the same to amplify sound waves.

Another feature of my invention is an improved mounting for the movable part of a valve for reproducing and amplifying sound waves.

Still another feature of the invention is an improved air pressure regulator for sound amplifying devices.

Other features of the invention the description thereof progresses.

In the accompanying drawings:

Fig. 1 is a central longitudinal sectional elevation through a unit embodying my invention, taken on lines I-l of Fig. 2.

Fig. 2 is a plan view of the structure illustrated in Fig. 1 with the cover removed.

F1l igl. 3 is a plan view of the structure shown in Fig. 4 is a perspective view of the linkage means extending between the armature and the dampening diagram.

Fig. 5 is a perspective exploded view, taken from the underside, of the air controlling valve.

Fig. 6 is a top plan view of the air valve seat located at the outlet end of the air discharge orifice of the structure shown in Fig. 1.

Fig. 7 is a perspective view of one element of the magnet structure associated with the voice coil for operating the air valve.

Referring to the drawings, ll designates the base, preferably of non-magnetic material such as bronze or the like, on one face of which is sewill appear as cured by screws ii a cover or enclosure i2, said screws passing through the perforations II. and spaced about the peripheral edge of the base II. Interposed between the base ill and cover I: is a gasket H which assists in maintaining an airtight Joint between said base ii and cover II. There is thus formed by the base l and cover I! a chamber iii to which may be supplied air under pressure. The supplied air is furnished by any suitable source of air under pressure, and the pressure or such air within the chamber is governed by an air pressure regulator forming part of the unit and located in the chamber II.

at one end of the base ll there is an outwardly extending boss I internally threaded to receive one end of a. nipple ll which may be connected at its outer end with a pipe or other suitable conduit leading to the source of air under pressure. On the base II and within the chamber II, is a projection II through which the nipple ll extends.

Secured to the projection II by screws i9 is a cage 10 of foraminous material, such as bronze or copper mesh, and covered with fabric 200 as shown. This cage is provided for the purpose of preventing access to the pressure chamber ll of solid foreign substances which may have passed through the nipple i l from the source of supply of air under pressure.

The base i0 is also provided on its lower face with a downwardly extending boss II. and on its upper lace with an upwardly extending boss 22 in substantial alignment therewith. Passing through the bosses I! and 21 is a passage 23 through which air may be passed from the chamber ii to the outer atmosphere through an attached horn (not shown). The lower or outer end of boss 2| is externally threaded at 24 to receive a coupling tor connecting the passage 28 with any suitable sound amplifyin device, as a horn.

The upper or inner end of the boss 22 has secured thereto in any suitable manner a. valve seat 25. This valve seat is constructed of suitable metal such as aluminum, bronze, or the like, and is provided with a plurality of parallelly arranged slots 28 cut in and through the material of the valve seat, thus defining a plurality of parallelly arranged bars "a separated from each other by the slots 28. These bars a and slots 28 collectively define a substantially rectangular area, see Fig. 6. The upper end of the passage 28 in the boss II is flared outwardly to define a substantially rectangular cavity ll equal in superficial area at its top end to the area defined by the bars 28a and slots 2!.

Cooperating with the valve seat 25 is a valve 21 formed essentially of a rectangular plate of suitable metal. The valve includes a plurality 01' bars arranged parallel to and spaced apart from each other and cooperates with the valve seat 25 to permit passage of air under pressure from the chamber II to the passage 23 and attached horn. As the bars of the valve 21 are very thin and relatively wide, they are flexible and may vibrate, rattle and bend out of shape due to the pressure and flow of air through the valve unless measures were taken to prevent the same.

Valve 21 is constructed by providing a plurality of holes 28 arranged parallel to each other and extending through the material of the valve parallel to the working or under face thereof. A number of slots 29 parallel to each other are cut into the under or working face only, of the valve,

0 lower end oi a cylindrical bar ll.

such slots II communicating with the holes 2|. The slots 2! are mutually separated by parallelly arranged bars II. The slots do not extend beyond the tops of the holes II, and, thereiore, the bars 82 are each supported at a plurality of points along their length by being integral at such points with the material of the valve 21. The slots 29 and bars 92 collectively define a substantially rectangular area in the working race of the valve and this area is equal to the area defined by the bars Illa and slots 2! of the valve seat 2. When in operative position the valve 21 has the bars 02 thereof disposed immediately above the slots 26 of the valve seat 25.

The valve 21 is riveted at one end to a cross-bar IQ and such cross-bar is secured by screws ll to spaced abutments Ila formed integral with an extending upwardly from the base ll. Secured in any suitable manner to the end of the valve 21 at the end remote from the cross-bar II, is an armature plate 32 of magnetic material, such as iron. At the end of the plate I2 remote lrom the valve 21 is a flat spring II, of phosphor bronze or the like, to the upper and lower surfaces of which are attached the reinforcing plates I and 85, respectively. Through the spring II and plates 34 and 35 extend the holes II and 81. Through the hole ll passes a screw II which screws into a threaded hole in the base Ill. The screw 38 secures the free end of the spring SI and plates 84 and 35 rigidly to the base II, a collar or sleeve I! being placed between the lower face of the plate 35 and the upper surface or the base II), as clearly shown in Fig. l. The valve 21 is, therefore, firmly secured at each end to suitable abutments.

Through the hole 36 is slidably mounted a threaded member III. This threaded member ll is formed integral with, and is located at, the

On the threaded member 40 and in engagement with the upper and lower surfaces of the plates N and SI, respectively, are washers l2 and 4!, respectively. screwing onto the threaded member in and in engagement with the'washer I! is a nut ll. Surrounding the threaded member ill and lying between the washer l2 and the lower end or the cylindrical bar 41 is a compression spring 4!. The vibrations of the valve 21 are, therefore, transmitted to the cylindrical bar ll.

Secured to, or formed integral with the base II and extending upwardly therefrom is a U-shaped standard 66, in the arms of which are pivot bearing members 41 carrying the lock nuts 48. Mounted on the pivot bearing members U and between the arms of the U-shaped standard 46 is the lower end of a lever 49. The lever 48 extends upwardly from the pivoted bearings I1, and thence extends substantially parallel to, but spaced apart from, the upper surface of the base The horizontal portion of the vibration transmitting lever 45 is drilled to provide a passage for the cylindrical bar 4|, mounted on or formed integral with the threaded member 40. The cylindrical bar 4! is secured in position in the arm 48 by means of a set screw 50. Therefore, the vibrations of the valve 21 are transmitted to the lever arm 45.

The free end of the lever 49 is provided with a perforation through which extends the threaded end of a shaft 5!. This shaft is formed integral with a cylindrical bar 52 rotatably mounted in a boss 53 formed integral with the base Ill. The Shaft ii is provided with a slotted head 54, ac-

cessible from the exterior or the chamber ll, or otherwise located on the outer face of the base it.

On the upper surface of the free end oi the lever ll and through which the shalt 5i extends is a vibration absorbing washer ll. Fitting over the vibration absorbing washer 95 is a metallic saddle ll which has secured thereto by soldering, or in'any other convenient manner. the lower end oi. a compression spring '1. Threading on the shaft Ii is an adjusting nut it which engases with and adjusts the tension of the compression spring I1. The under-surface of the lever arm ll, adjacent the free end thereof, has its downward movement limited by the engagement thereof with the cross-bar 30 to which is secured the valve 21, and when the device is not in use this is the normal position of the arm 49. Further. the compression spring tends to force the lever arm into engagement with the crossbar 30. The tension of the spring 51 may be adlusted from the outside of the device by means of the slotted head ll of the shait 5i.

Secured to the extreme end of the vibration transmitting arm 48 by means of the screw as and reslient member 80 is a threaded member M. This threaded member 6| has threaded thereon a nut 82 and also carries thereon a disc 63. Mounted on the disc 63 and also on the threaded member ii is a diaphragm 8| of resilient material, such as rubber or the like, and on the upper surface of the diaphragm II is a second disc 6!. a nut it being employed to hold the diaphragm in position.

The diaphragm N is preferably circular in form and is seated in a counterbored portion 61 in the upper surface oi the cover i2. The diaphragm i4 is secured in such counterbored portion by a plurality screws 88 and annular plate ILL MA cover plate 10, held in posit on by screws I I, closes the counterbored portion 51.

The construction above described is such that when no air under pressure is being delivered to the chamber I through the nipple H, the valve 21 will be in air-tight engagement with the valve seat 25. This is highly important as it keeps dirt and other particles of foreign matter from getting in between the valve and valve seat when the device is not in operation.

When air under pressure enters the chamber II, the diaphragm H is flexed upwardly thus raising, by means 01' the threaded member iii, the free end of the lever 49, with the result that the spring Ii is compressed and the valve 21 is lifted off the valve seat 25, thus permitting flow of air through the valve structure into the passage 23. The amount oi lift of the valve 21 is determined by the adjustment of the spring Bi and thus this construction acts as a pressure regulator. The device therefore will maintain a constant pressure within the chamber I5.

This constant pressure automatically suspends the valve 21 in a position that allows for the most efl'ective modulation of the air stream. 11' the air be considered a molecular structure, and such structure being compressed, the degree of compression is determined by pressure. The valve structure not only utilizes the pressure of the air, but also the energy of its moving part cles, 1. e. the kinetic energy of the air molecules.

A further function of the above described pressure controlling device is to prevent the gradual forcing of the valve into absolute closing relation with the valve seat under pressure. Without it. the pressure would rise at the pump, lockin: the valve and valve seat together and the result would in all probability be a burned out use or motor.

The above described structure also makes it uhnecessary to have a pressure gauge or safety valve on the air supply or pump. All 0! these desirable results are possible because of in. location or the valve structure in the high pressure side of the valve. All other things being equal, the valve located in the high pressure side increases the sound intensity from live to eight times.

Surrounding the armature plate 3! ol masnetic material and resting on top 0! the base II is a voice coil 12. This voice coil is connected by conductors 13 and 1| to terminals 15 and 12 respectively. These terminals extend through the base ill. but are insulated therefrom in the usual manner. and associated therewith on the exterior of the base ll are binding posts 11 (but one of which is shown) by means of which the voice coil 12 may be electrically connected to a sound transmitting mechanism, such as telephone transmit tel.

Surrounding the voice coil 12 is a magnet systern including pole pieces 18, the terminals 1| of which are spaced apart laterally and vertically from each other, as shown in Figure 7. The armature plate 32 extends between the upper and lower terminals of each pole piece; the voice coil 12 is supported in vertical position by the spaced. forwardly extending side walls "a, Ila oi the pole pieces 1|. Associated with the pole pieces 1' is the permanent ma net Ii.

Assume the device to be constructed as above described. and that a conduit from a source of air under pressure is attached to the nipple l1.

while an amplifying horn (not shown) is attached to the threaded portion 24 of the boss 2i, and that the parts have been adjusted properly and are in the position shown in Fig. 1. When the t0 operator allows the air under pressure to flow from the source of supply to the chamber ii, the diaphragm 06 will be flexed upwardly, lifting the free end oi the lever 48, thereby compressing the spring Bi and relieving the pressure of the valve 21 with respect to its valve seat 25 under the ore-set regulation of the regulating spring 5|, adjusted by its nut it. By such arrangement air is permitted to flow beneath the valve 21 as well as through the openings 2! and slots 28 of the valve 21 and thus into the discharge passage 23, thereby rendering the valve 21 sensitively responsive in vibration to the vibration of the armature I2, actuated by the voice coil 12, and maintaining substantially constant pressure within the chamber it. As above set out. by reason of the armature 32 being resiliently mounted at its one end by means of its i'lat spring l3 and the cross bar 30 supporting the valve 21 at one end. the armature 82 being rigidly connected with the valve 21 at their respective opposite ends, modulation of the air flow into and through the discharge opening 23 is effected by the vibration of the valve 21 in faithful response to the voice currents passing through the voice coil 12, as well as maintaining the pressure oi the air within the chamber l5 substantially constant.

The operator will then speak into the transmitter (not shown but above referred to) thereby producing an undulatory current in the voice coil 12. Such current causes the armature plate I2 attached to the valve 21 to vibrate said valve, moving the same rapidly and in accordance with the voice currents, toward and away from the valve seat 25.

In order to prevent the harshness which appears to be inherent in devices of this character, it will be noted that the same is practically "deadbeat" in that one end 01 the valve 21 is anchored to the cross-bar l and the other end is anchored to the base ID by means of the screw I8. Any vibration that is imparted to the valve 21 will likewise be imparted to the resilient plate 33 and plates 14 and 3!, associated therewith, and such vibration will be transmitted through the cylindrical bar H to the lever arm II. The vibrations transmitted to the lever arm 1. will be partially damped out by the resilient spring II mounted on the free end or the damping and pressure regulating arm Cl and will be further and practically totally damped out by means of the diaphragm I! attached to the free endoi the arm ll through the threaded member it. Q

Whereas I have described my invention by reference to specific forms thereof, it will be understood that many changes and modifications may be made without departing from the spirit of the invention.

I claim:

1. An improved amplifier including, in combination, a closed chamber for holding air under relatively constant pressure, inlet means for said closed chamber arranged to be connected to a pressure air supply, an outlet for said chamber, a valve seat extending across said outlet, a valve disposed within said chamber, resilient means for mounting said relative to said valve seat, an armature associated with said valve, a voice coil for controlling the movements 01' said armature in synchronism with voice currents transmitted through said voice coil. said closed chamber being further provided with an opening, a diaphragm disposed within and closing said opening, and pivoted lever means associated with said diaphragm and with said armature, whereby under the condition oi supplied compressed air within said chamber, said diaphragm functions to displace said valve relative to its said valve seat and render said valve responsive to vibrations oi said armature induced by voice currents through said voice coil while maintaining substantially predetermined air pressure within said closed chamber.

2. An improved amplifier unit comprising a pressure casing, an entrance passage communicating with the casing for introducing air under pressure within the casing, an exit passage irom said casing, a valve seat provided at the end of said exit passage within the casing, a valve disposed above said valve seat and arransed for vertical movement with respect thereto, an armature connected to said valve, a motor system including a voice coil and a magnet system. said magnet system having pole pieces disposed on opposite sides of said armature for vibrating the same, said casing being provided with an opening, a flexible diaphragm disposed in and closing said opening oi said casing and subject to the pressure therein. and a lever operatlvely associating said armature and said diaphragm. whereby movement of said flexible diaphragm under the influence of pressure within said casing adiimts the position oi said valve with respect to said valve seat and said diaphragm additionally serves as means for dampening the vibrations of said armature.

3. In animproved amplifier, the combination of an air pressure chamber, an outlet for said chamher, a valve seat extending across said outlet, a valve disposed within said pressure chamber and cooperating with said valve seat ior controlling the emission of air from the chamber through the outlet, means for supporting said valve at one end thereof, an armature secured at its one 6 end to said valve, flexible means for supporting said armature at its other end, electromotor means for vibrating said armature. a pivoted lever secured adjacent one end to said armature, spring means biasing saldlever to urge the armature and 10 therewith associated valve in the direction of said valve seat, and a flexible diahpragm responsive to air pressure within the casing and operatively associated with said lever to displace the same in opposition to said spring means upon increased air pressure within the chamber, thereby moving said armature and said valve away from said valve seat.

4. An improved sound amplifier comprising, in combination, a hollow chamber provided with inlet means arransed to be connected to a pressure air supply, said chamber being provided with an outlet, said chamber otherwise closed to the outer atmosphere; a grid associated with said outlet; a valve dispowd within said closed chamber and disposed inwardly of said grid; resilient means for mounting said valve in close association with said grid and said outlet; said closed chamber being provided with an opening, diaphragm means closing said opening; lever means operatively connecting said diaphragm with said valve: eiectro-magnetic means including an armsture associated with said valve; and resilient means for mounting said armature.

5. An improved sound amplifier comprising, in combination. a hollow chamber provided with inlet means arranged to be connected to a pressure air supply, said chamber being provided with an outlet, said chamber otherwise closed to the outer atmosphere; a grid associated with said outlet: a -valve disposed within said closed chamber and disposed inwardly oi said grid; resilient means for mounting said valve in close association with said grid and said outlet; said closed chamber being provided with an opening, diaphragm means closing said opening; lever means operatively connecting said diaphragm with said valve; resilient means for damping said lever means; electromagnetic means including an armature associated with said valve; and resilient means for mounting said armature.

6. An improved amplifier including, in combination, a closed chamber for holding air under pressure, said chamber being provided with an inlet arranged to be connected with a pressure air supply, an outlet for said chamber, a valve seat extending across said outlet, a. valve disposed within said chamber and associated with the valve seat, means for suspending the valve away from but in controlled association with the valve seat, said closed chamber being further provided with an opening, diaphragm means closing said opening, electro-magnetic means controlling the valve, lever means operatively connecting said diaphragm means and the valve for controlling the position of the valve with respect to the valve seat, and regulatable resilient means for controlling the displacement of the lever means.

7. An improved valve for sound amplifying devices, comprising a relatively thick rectangular body, a plurality of closely spaced parallelly arranged slots cut into one face, only, of said body and extending longitudinally thereof and a pinrality of relatively closely spaced holes drilled through the body from side wall to side wall lies and a plurality of parallelly arranged grooves formed in the working face of the valve and communicating with the plurality of perforations, whereby a valve structure having a working face including a. plurality of extremely thin bars is attained and in which such bars are free of vibration under the influence of moving air.

CHARLES F. DILKS.

Certificate of Correction Patent N 0. 2,384,371.

September 4, 1945.

CHARLES F. DILKS It 1s hereby certified that error appears in the printed specification of the above numbered patent re luring correction as follows: Page 4, first column, line 32, claim 1, before the word re etive insert valve; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 3rd day of December, A. D. 1946.

LESLIE FRAZER,

First Assistant Hominiuioner of Patents.

lies and a plurality of parallelly arranged grooves formed in the working face of the valve and communicating with the plurality of perforations, whereby a valve structure having a working face including a. plurality of extremely thin bars is attained and in which such bars are free of vibration under the influence of moving air.

CHARLES F. DILKS.

Certificate of Correction Patent N 0. 2,384,371.

September 4, 1945.

CHARLES F. DILKS It 1s hereby certified that error appears in the printed specification of the above numbered patent re luring correction as follows: Page 4, first column, line 32, claim 1, before the word re etive insert valve; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 3rd day of December, A. D. 1946.

LESLIE FRAZER,

First Assistant Hominiuioner of Patents. 

